Harding tells Us no 911 call was received, and that she was not sure if Barton, 23, was in distress. When asked if the actress was cooperative, she tells Us: "I guess." Harding did not release details on where Barton was taken, citing California privacy laws. But Access Hollywood reports Barton was placed under an involuntary psychiatric hold (also known as a 5150) by the Los Angeles Police Department before being transferred to Cedars-Sinai Medical Center. (According to the code, authorities can hold a person involuntarily if they present a danger to themselves or others. This same code was used to hold Britney Spears twice in Los Angeles in January 2008.) In a statement, Barton's rep Craig Schneider tells Us: "Police were involved due to Ms. Barton's celebrity status; to ensure her safe transfer to medical treatment for which she remains hospitalized as per the recommendation of her doctor."

A source tells Us Barton called the police herself after having a "freak out." Barton won't be at the NYC premiere of her new movie, Homecoming, tonight, an event rep tells Us. The actress -- best known for her role on The O.C. -- was charged in 2008 with DUI and marijuana possession. She was sentenced to 36 months probation, told to attend alcohol education classes and pay a fine. Barton checked into rehab after the incident, she said, because "I wanted to prove to the court that I would take it completely seriously.